1) Field of the Invention
The present invention relates to a latch device of a biaxial hinge tailgate that can be selectively released to open about two axes having different axial directions, wherein, upon selection of one axis for tailgate release, the tailgate release about the other axis is disabled, the latch device of the biaxial hinge tailgate including hinge latch mechanisms which assume a disengaged condition if the tailgate is released about one axis and latched if the tailgate is released about the other axis.
2) Description of the Related Art
In conventional station wagon type vehicles, a biaxial hinge tailgate allows selection of the tailgate movement from a substantially vertical position to a position assumed upon release of the tailgate by movement about a horizontal shaft provided on the bottom of the tailgate (flap-type release) or about a vertical shaft provided either on the left side or on the right side of the tailgate (swing-type release).
This type of biaxial tailgate has on the bottom left corner a multi-axis hinge that joins the tailgate. The multi-axis hinge includes a horizontal shaft and a vertical shaft. The biaxial tailgate is also provided with a latch device that can realize the swing-type release or the flap-type release described above. The latch device includes, on the lower right portion of the tailgate, a horizontal hinge latch mechanism which can swing about the horizontal shaft of the multi-axis hinge and which engages with/disengages from the vehicle body. A vertical hinge latch mechanism which can swing about the vertical shaft of the multi-axis hinge and which engages with/disengages from the vehicle body is provided on the upper left portion of the tailgate. A common latch mechanism, which engages with/disengages from the vehicle body, is provided on the upper right portion of the tailgate. A flap actuation handle is provided centrally on the inside (or outside) of the tailgate for unlatching the common latch mechanism and the horizontal hinge latch mechanism. A swing actuation handle is provided externally (or interiorly) on the tailgate for unlatching the common latch mechanism and the horizontal hinge latch mechanism. The common latch mechanism and the vertical hinge latch mechanism are disengaged by actuating the flap actuation handle, and flap-type release of the tailgate is realized by the turning of the horizontal shaft of the multi-axis hinge and the horizontal hinge latch mechanism. Likewise, the common latch mechanism and the horizontal hinge latch mechanism are disengaged by actuating the swing actuation handle, and swing-type release of the tailgate is realized by the turning of the vertical shaft of the multi-axis hinge and the vertical hinge latch mechanism.
Disengagement of all three latch mechanisms, namely, the horizontal hinge latch mechanism, the vertical hinge latch mechanism, and the common latch mechanism, is prevented upon redundant actuation of the swing actuation handle and the flap actuation handle of the biaxial hinge tailgate latch device. The common latch mechanism of the latch device includes a latch that engages with a striker fixed on the vehicle body, and a ratchet that both maintains and releases the engagement of the latch. The latch device has two release levers (a flap release lever and a swing release lever) that carry out the actuation of the ratchet in order to disengage the latch of the common latch mechanism. The flap release lever is actuated by actuating the flap actuation handle, and the swing release lever is actuated by actuating the swing actuation handle. One side of both the levers is actuated by the ratchet while actuation is throttled on the other side due to the levers coming in contact with one another. The horizontal hinge latch mechanism is linked to the swing release lever, and disengages with the disengagement of the common latch mechanism due to the swing actuation handle. The vertical hinge latch mechanism is linked to the flap release lever, and disengages with the disengagement of the common latch mechanism due to the flap actuation handle.
In the biaxial hinge tailgate latch device that has the structure described above, the flap release lever, which is flap actuation handle-actuated, obstructs the path of the swing release lever while disengaging the common latch mechanism and the horizontal hinge latch mechanism. In other words, when the flap release lever is actuated, it obstructs the swing release lever, which is swing actuation handle-actuated, and disables the actuation of the swing actuation handle by preventing the actuation of the swing movement lever and the disengagement of the vertical hinge latch mechanism. Similarly, the swing release lever, which is swing actuation handle-actuated, obstructs the path of the flap release lever while disengaging the common latch mechanism and the vertical hinge latch mechanism. In other words, when the swing release lever is actuated, it obstructs the flap release lever, which is flap actuation handle-actuated, and disables the actuation of the flap actuation handle by preventing the actuation of the flap movement lever and the disengagement of the horizontal hinge latch mechanism.
In the biaxial hinge tailgate latch device that has the structure described above, when the tailgate is opened by actuating the swing actuation handle, the vertical hinge latch mechanism turns. In other words, when the vertical hinge latch mechanism provided on the tailgate and the striker provided on the vehicle body are engaged, the striker acts as the shaft that turns the vertical hinge latch mechanism. On the other hand, when the tailgate is opened by actuating the flap actuation handle, the horizontal latch mechanism turns. In other words, when the horizontal hinge latch mechanism provided on the tailgate and the striker provided on the vehicle body are engaged, the striker acts as the shaft that turns the horizontal latch mechanism. Conventional techniques have been disclosed in, for instance, Japanese Patent Laid-Open Publication No. S50-3533, U.S. Pat. No. 3,454,299, U.S. Pat. No. 3,592,504, and U.S. Pat. No. 4,076,301.
However, in the conventional biaxial hinge tailgate latch device, upon redundant actuation of the swing actuation handle and the latch movement handle, the actuation that first disengages the common latch mechanism overrides the other. The movement of the flap release lever or the swing release lever, whichever releases the common latch mechanism, disables the movement of the other by obstructing its movement. Thus, in the conventional tailgate latch device, the common latch mechanism, which is always functional, has to have a complicated structure in order to disable either one of the handle actuations during both flap release and swing release. Further, the common latch mechanism bears the brunt of the load since the provision of structure that causes obstruction concerns the common latch mechanism.
Further, in the conventional biaxial hinge tailgate latch device, if both the swing actuation handle and the flap actuation handle are simultaneously actuated, neither of the handle actuations can be disabled until the common latch mechanism is disengaged. Consequently, which handle actuation was in force cannot be determined until the tailgate actually moves.
Again, in the conventional biaxial hinge tailgate latch device, separate swing actuation handle and flap actuation handle are provided on the tailgate externally and interiorly. This increases the chance of different persons redundantly actuating the swing actuation handle and the flap actuation handle, leading to frequent occurrence of the above-described problem.
In the conventional biaxial hinge tailgate latch device, the vertical hinge latch mechanism and the horizontal hinge latch mechanism engage with the striker by means of the latch. When the hinge latch mechanism turns, the latch can be made to slide rotate with respect to the fixed striker. This however will result in the wearing away of the resin material on the latch provided in order to prevent noise due to contact with the striker.
Alternatively, the hinge latch mechanism may be turned by supporting the striker to make it rotatable with respect to the vehicle body by means of bearings, etc. However, the bearings are not durable enough to be able to withstand an anticipated load of 300 kg to 400 kg.